Soot blower



A. M. WILSON SCOT-BLOWER Oct. 13, 1942.

Filed Feb. 13, 1941 2 Sheets-Sheet 2 lllll Patented Oct. 13, 1942 UNITEDSTATES PATENT OFFICE SOOT BLOWER Allan Murray Wilson, Clydebank,Scotland Application February 13, 1941, Serial No. 378,727 In GreatBritain November 11, 1939 3 Claims.

This invention relates to soot-blowers which are used in associationwith steam-boilers and other heat exchangers for the purpose ofperiodically ejecting cleaning fluid (namely steam) on tubes and otherparts to remove soot, scale and other matter likely to be depositedthereon.

Soot-blowers are known in which, when the blower is operative, acomponent moves to-andfro lengthwise of the blower, and it is tosootblowers 'of this type that the present invention relates. Usually,said component is the fluid ejector, which comprises a nozzle elementand a tube on which the nozzle element is provided, and said componentis movable axially between an inoperative range in which it is shelteredfrom the heat of the furnace or other zone in the heat exchanger and anoperative range in which cleaning fluid is ejected on the parts to becleaned.

The invention is particularly, although not exclusively, applicable tosoot-blowers of the type stated in which the motion of the fluid ejectoris controlled by a screw device and a cam device, the screw deviceserving to move the fluid ejector to and from the operative range andthe cam device serving to turn, or control turning of, the ejectorangularly when in the operative range so as to sweep the fluid over theparts to be cleaned.

An object of the present invention is to make provision whereby asoot-blower of the type stated will be rendered more suitable thanheretofore for direct connection to a high pressure system (for example,to steam piping delivering cleaning steam at pressures ranging upwardsfrom a thousand lbs. per square inch).

Another object of the invention is to provide in a soot-blower embodyingin its construction a valve which passes cleaning fluid to the fluidejector when the ejector is in its operative range of motion and cutsoff the cleaning fluid when the ejector is in its inoperative range, apressurereducing valve in interlocked relationship with the soot-blowervalve, so that both valves open and close approximately in unison withone another.

Another object of the invention is to operate such a pressure-reducingvalve, which may be a nearly balanced valve, by the to-and-fro movablecomponent of the soot-blower to cut-off the supply of cleaning fluid tothe soot-blower valve while the ejector is in its inoperative range.

Other objects of the invention will be clear from the followingspecification and claims.

An embodiment of the invention will now be 55 described by way ofexample with reference to the accompanying drawings, in which:

Fig. 1 is a sectional elevation of a soot-blower having, the inventionapplied thereto.

'Figs. 2 and 3 are sections, each drawn to a larger scale than Fig. 1,of constructional details.

The steam ejector comprises a tubular unit II], II, I2 extending througha steam chest I3. A wall box I4 forming an extension of the chest I3 isadapted to be mounted on a boiler wall A or other structure. The tubularunit includes a ported portion II which works as an internal sleevevalve in a ported cylinder I5 forming an integral extension of the steamchest. The respective ports are denoted HA and I5A. The tubular unit isconnected at the end opposite the nozzle II] to a nut I6 (Fig. 3)forming one element of a screw device of which the male element I1 is ascrew rotatable manually or by power, through the intermediary of screwgears I8.

A pin IGA which projects from the nut I6 engages in a cam slot I9A, I9Bcut in a casing 20 which constitutes a detachable extension of the steamchest I3. As Fig. 1 shows, the portion ISA of the cam slot is straight,whereas the portion I9B is cut helically at a steep inclination. Thecasing 20 forms a support and bearing for an angularly adjustable casing2i in which the screw gears l8 are housed.

In operation, the screw I1 is rotated first in one direction to advancethe tubular unit I0, I I, I2 into a position in which the. nozzle I0projects from the boiler wall into the interior of the boiler furnace orother zone. During the advance of pin I6A along the straight portion I9Aof the cam slot, no rotation of the unit I0, I I, I2 occurs. As soon asthe range represented by the portion I9B is reached by pin I6A, the unitrotates as it advances. The screw I1 is turned back and forth anydesired number of times to the extent of the range represented by theportion I9B, and in this motion the nozzle moves to and fro endwise Fbeyond the boiler wall and turns to and fro in its motion. Finally, theunit I0, II, I2 is fully withdrawn into the inoperative position inwhich it is shown in full lines in Fig. 1.

There is provided in inter-locked relationship with the blower sleevevalve II a valve assembly which reduces the pressure of steam passingthrough it to the sleeve valve. The nature of the interlock is such thatsteam is passed to the sleeve valve only when the ejector I0 is in theoperative range, the valve assembly automatically cutting off steam fromthe sleeve valve whenever the ejector is inoperative.

The pressure-reducing valve assembly includes a spring-loadedpressure-reducing valve 22, to which high pressure steam is suppliedfrom an internal source. As shown the valve 22 may be similar in,construction to a known type of safety valve with external spring. Thevalve 22 is arranged to control, the steam-conduit 23 leading to thesoot-blower sleeve valve II. The spring 24 is housed in a fixed casing25. The valve proper 26 is maintained in operative relationship with itsseat 21 by a pointed stem 28 which is connected with the valve casing bya flexible diaphragm 29. The closing pressure exerted on the valveproper by the spring is regulatable by an adjustable abutment 30, whichis screwed into the spring casing 25.

The pressure-reducing valve is connected by a mechanical transmissionconstituted'as a linkand-lever mechanism to a cam followerwhich isactuated by a cam moving with the tubular unit I 0, l I, I2 of thesoot-blower. The said mechanism comprises a bell-crank lever 3|, 32fulcrumed at 33 on the spring casing 25, one arm 31 being slotted toreceive a pin 34 projecting through the casing 25 from the spring seat35 on the valve stem 28 and the other arm 32 having a pin-and-slotconnection at 36 with a link 31, 38. A turnbuckle 39 interposed betweenthe link components 31 and 38 serves to adjust the otherwise fixedextent of valve opening by the cam action. The cam follower is a ball 40carried by the link component 38, which is guided through a bush 38A onthe casing 20. The cam is a sleeve 4| on the nut 16, said cam includinga conical face MA.

The spring load is set so as to be some predetermined comparativelysmall amount, say 100 lbs., in excess of the thrust due to the steampressure on the valve proper when closed. That is, when the valve isclosed it is nearly balanced.

In operation, the cam mechanism forces the pressure-reducing valve toopen just as the blower valv II is being or has been opened and permitsthe pressure-reducing valve to close under limited to this minute liftbecause the spring 24 imposes on the valve a load which is greater thanthe opposing steam pressure on the valve. effect of the limited minuteopening of the valve is to provide a constriction which finely wiredrawsthe high pressure steam and thus greatly reduces the pressure of thesteam which accordingly reaches the ports HA of the tubular unit II],II, I2 in a low pressure condition.

The abutment 30 can be utilised as a means of forcing the valve to closeand remain closed in in opposition to the steam pressure. Thus, byscrewing down the valve in this way one can isolate the soot-blower fromthe steam system. Thus, if any part of the blower is out of order,

The

the blower can be partly dismantled for inspection or repair.

An example of a soot-blower to which my present invention is applicableis described in my United States Patent 1,773,801.

I claim:

1. In a soot blower of the type comprising a tubular unit movable to andfro lengthwise of the interior of the blower in the operation thereofand embodying in its structure a nozzle and a sleeve valve which opensto pass cleaning steam to said nozzle only when the nozzle is inoperative position, a conduit supplying cleaning steam to said sleevevalve, screw means applied to said unit for moving said unit so thatsaid nozzle moves to and from said operative position, and a cam deviceapplied to said unit and co-operating with said screw means to impart arotational motion to the nozzle when in said operative range, thecombination of a pressure-reducing valve in said conduit subjected to avalve-opening force by the steam, a valve-closing spring arrangedexternal to the blower interior and adapted to act on said reducingvalve in opposition to and with a force greater than the valve-openingforce of the steam, a valve-opening mechanism applied to said reducingvalve, and a cam on said tubular unit acting on said mechanism inco-operation with said spring to open said reducing valve to a fixedminute extent providing a constricted opening as said sleeve valve isopened under control of said screw means so that said reducing valvewiredraws the steam and reduces it in pressure for passage through saidsleeve valve to said unit.

2. In a soot blower of the type including a tubular ejector movable intoan operative zone, and an internal valve provided on said ejector andopened by endwise movement thereof into the operative zone to admitcleaning steam to said ejector, a steam conduit leading from a source ofhigh pressure steam to said internal valve, an additional valve in saidconduit, a cam on said ejector, a mechanical transmission applied tosaid additional valve and operable by said cam to force and maintainsaid additionl valve slightly open to provide a constricted opening whensaid ejector is moved endwise to open said internal valve, and a springlimiting said additional valve to the constricted opening enforced bysaid cam and said transmission, so that said additional valve wiredrawsthe high pressure steam and reduces it to low pressure steam for saidejector.

3. In a soot blower of the type including a movable ejector unit and avalve opened by endwise movement thereof to admit cleaning steamthereto, a conduit for ingoing steam to said valve, a second valve insaid conduit, a mechanical transmission applied to said second valve,means of said unit actuating'said transmission to force and maintainsaid second valve slightly open and provide a constricted opening whensaid unit is moved endwise to open the first-mentioned valve, and meanslimiting said second valve to the constricted opening enforced by saidtransmission so that said second valve wiredraws the ingoing steam andreduces it in pressure for said unit.

ALLAN MURRAY WILSON.

